The invention relates to a fuel injection nozzle for internal combustion engines, in particular those with direct injection, as generically defined hereinafter. In an injection nozzle of this type, known from European Patent Disclosure EP-A-209 244, the sealing seat, formed by the valve seat and the valve cone and having a circular linear form, is formed on the radially outer circumference of the valve seat or valve cone in that the cone angle of the valve seat on the nozzle body is smaller than the cone angle of the valve cone at the closing head of the valve needle. Moreover, the control edge at the transition from the valve seat to the guide portion of the nozzle body is rounded. This embodiment forms an annular gap of wedge-shaped cross section between the face of the valve seat and the valve cone and the circumference of the guide portion of the valve needle; in this annular gap, fuel collects aligned with the opening cross section of the injection ports of the valve needle when the valve is closed; especially at the injection onset, this collected fuel hinders stream preparation. Moreover, the fuel streams emerging from the injection ports sometimes strike the rounded portion and the faces tapering outward of the valve seat and valve cone, leading to an energy loss for fuel preparation.
A similar fuel injection nozzle is disclosed by U.S. Pat. No. 2,035,203; in it, the valve needle has a shaft with the closing head and sleeve surrounding the shaft that covers the longitudinal grooves in the shaft and that has slits in its face end oriented toward the valve that form injection ports of a defined cross section. In this known injection nozzle, although good stream preparation is attained, the tightness of its valve leaves something to be desired, because of the flat seat between the valve cone and the valve seat. This disadvantage is made even worse by the fact that the valve needle with the valve cone and the sleeve mounted is guided in the nozzle body, and so the tight seat fit is displaced by an offset of the axes of these components.